What are the elements of equitable estoppel?

The elements of equitable estoppel are not shown in the record, "[E]stoppel requires some affirmative representation or acts by the public agency or its representatives inducing reliance by the claimant." (Tammen v. County of San Diego (1967) 66 Cal.2d 468, 480-81, 58 Cal.Rptr. 249, 426 P.2d 753, and see City of Long Beach v. Mansell (1970) 3 Cal.3d 462, 488-89, 91 Cal.Rptr. 23, 476 P.2d 423.) Our independent search of the record discloses no such affirmative act or representation on the party of the County of Santa Clara.